This is Reptor/xorcoder from Germany again. Yesterday I resumed work on bfxor, my brute-forcing tool with which it's possible to hack XOR encrypted data, mostly text, up to 64-bit keys (8 chars). The ...

I have two ciphertexts, I suppose that its RC4 with reused key. I have XORed both ciphertexts and obtained message containing combined cleartexts.
I suppose that the underlaying messages are written ...

I'm trying to understand how a XOR affect traces of power consumption in a Differential Power Analysis on smartcards.
What's the difference in energy radiated in a $1 \oplus 1$ and in a $0 \oplus 1$?
...

I have a series of obfuscated strings which across the set of strings have regions of high variance and regions of low variance – implying some encoding mechanism as opposed to an encryption procedure ...

Ok, so I have this question and I honestly have no idea how to prove it. I know that the function is linear and I know it works for every possible combination, I just don't know how to prove it in an ...

One of the main rules of the OTP is, that a key should never ever be reused.
But if we use some commutative operation (XOR for example) for generating the cipher text, then I don't see any difference ...

I am currently trying to implement a very fast and simple encryption algorithm in Lua for the purpose of using it with ComputerCraft.
The main problem is that bitwise operations in Lua (5.2 at least) ...

Can anyone comment if the stream cipher described here is safe? The author claims it to be unbreakable, but does not provide any evidence or proof to support this. For completeness, I have reproduced ...

The question came up here, which left me thinking:
Is it possible to deduce the IV from CBC ciphered data, without knowing the key?
And if not, why is it considered a bad idea to create an IV by, for ...

I need to encrypt an ASCII string [a-zA-Z0-9:] to an ASCII [a-zA-Z0-9] string of the same length. It doesn't have to be unbreakable, it's sufficient that it won't be readable at the first sight.
The ...

I'm new in cryptography and try to read some articles in this field.
Many of these articles talk about non-linear S-boxes, and nothing more on what they mean by their non-linearity.
I have a simple ...

When implementing a XOR cipher with a pseudo-random key equal in length to the plaintext, Is there a significant difference in potential key strength between keys drawn from a pool of either 1000 or ...

If I have a long randomly generated key (k), XORed with a message (m), but since the message is longer than the key, there is a chance of reusing the keystream with the same message, but the key is ...

I was wondering how we can get a secret sharing of $a+b$ from the sharing of secrets $a$ and $b$ themselves by using an XOR secret sharing scheme, where $a_1,...,a_n$ and $b_1,...,b_n$ are the shares ...

I have a file containing 16-bit samples and I want to encrypt it, but the problem is that I need to be able to read any random 16-bit value from the file, and be to able to decrypt it, without reading ...

So I was thinking about variations on the Dining Cryptographers problem - In some cases, it's useful to be able to post a message without revealing the source, but with the additional constraint of ...

When analyzing a repeating-key xor cipher to find the key length, I've read about two key methods (assuming there aren't just repeating chunks of ciphertext for Kasiski's method), for some assumed key ...

I have a message $m_1$ and I want to encrypt it by XORing it with two keys $k_1$ and $k_2$:
$$c_1 = m_1 \oplus k_1 \oplus k_2$$
So far so good.
Now I was wondering if I could create a "fake" result ...

I read that to break repeating-key xor you can do the following: try a keysize $n$ and compute the hamming distance between the first $n$ bits of the encrypted string and the bits $n+1$ to $2n$ of the ...

I'm exploring ways of encrypting Intel hex files we send to customers for flashing onto an embedded device. The embedded processor itself has a built-in mechanism that prevents anyone from reading the ...

I am trying to break a packet format. The packet format simply packs several files into one big file. The file contents are plain. But the index data which contain offsets, file sizes and filenames ...